Abstract
Objectives
Hydroxytyrosol (HT) has been associated to health beneficial effects of extra virgin olive oil. Red wine is an indirect source of HT as it contains its precursor tyrosol (TYR), which is endogenously converted into HT. Beer is another source of TYR, which is originated during the fermentation as a secondary a metabolite of the amino acid tyrosine. The present work shows the first clinical study aimed at assessing the endogenous formation of HT following beer consumption.
Methods
Cross-over randomized clinical trial in healthy volunteers administered 250 mL of a dark beer (3.5 mg of TYR and 17.0 g alcohol), 250 mL of a lager beer (2.3 mg of TYR and 9.0 g alcohol), 250 mL of a non-alcoholic beer (1.4 mg of TYR and 0 g alcohol), and finally 150 mL of red wine (3.7 mg of TYR and 16.8 g alcohol). Urinary recovery of TYR and HT metabolites was quantified by LC/MS-MS.
Results
Results confirm that TYR present in beer is absorbed and endogenously converted into HT after its consumption (Figure 1). Nevertheless, the highest recovery was observed after red wine. Dark beer administration, which TYR and alcohol doses were equal to red wine, presented lower levels of TYR absorbed and hence, lower levels of HT generated. Lager and non-alcoholic beer presented dose-response absorption of TYR, but not an HT generation.
Conclusions
The present study is the first demonstrating that TYR present in beer is absorbed and endogenously biotransformed into HT in humans. HT generation is not TYR and alcohol dose-dependent and, is globally lower than following red wine, suggesting that other factors such as gas or other phenols could interfere in TYR bioavailability. Interestingly, HT recoveries after non-alcoholic beer are similar to those observed after alcoholic ones, limiting alcohol intake and the health and social problems associated to alcohol abuse. These findings could be relevant to understand the health effects associated to beer consumption.
Funding Sources
AB is recipient of a fellowship from ISCIII (PFIS), NS is recipient of a fellowship from Centro de Información Cerveza y Salud (Beca Manuel Oya) and CIBEROBN.
Supporting Tables, Images and/or Graphs
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